Yes, that's the case with the positioned layout. You can do one thing if you do not want to change every subform to a flow layout, then let it be positioned and wrap them under a subform with a flowable layout.

Yes, it will jump because you have made others as positioned. So make other flow as well. It will be good for future changes, if you need to add/delete any fields in the future then the flow layout is best, it adjusts the form itself. 

Use the flow layout for the Main page and for the subform if any are used in the form. Also, make the field expand to fit and make it multiline from the field property. 

Here you go! https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/forms/integrate/services/embed-adaptive-form-aem-sites.html?lang=en   Ensure that the AEM Form component is configured as an allowed component in the associated template in an AEM sites page.

https://stackoverflow.com/questions/74435561/aem-forms-adobe-form-submission-failure-on-publish-instance-error-code-aem-af   check this out, please.

Can you please share yours from @ (vkatoch07@gmail.com)? I'll have a look.

https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/forms/adaptive-forms-authoring/authoring-adaptive-forms-foundation-components/configure-forms-portal.html?lang=en   In AEM as cloud have below options, Please follow above article. Save Adaptive Forms As Drafts You can ...

You need to configure the Drafts & Submissions component. Have you seen the below article? https://experienceleague.adobe.com/docs/experience-manager-65/forms/publish-process-aem-forms/draft-submission-component.html?lang=en  

      https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/forms/adaptive-forms-authoring/authoring-adaptive-forms-foundation-components/generate-document-of-record-for-non-xfa-based-adaptive-forms.html?lang=en  

If the template is designed in AEM forms designer, then open it and see its pages or components used inside. Check if any invisible images or backgrounds are added.